Scavenge pump drive



Feb. 1s, 1947.

w. E, MEYl-:Rs

vS CAVENGE PU'lP DRIVE Filled Fab. 2e, 1945 3 sheets-sheet 1 INVENTR.

WlLLARD F. MEYEFIS.

By S

ATTDRNEY Feb. 1s, 1947..v

w. F. MEYERs scAvENGE Puur DRIVE:`

3 Sheets-Shet 2 Filed Feb. 26, 1945 V EN TOR.

` IN 9 WILLAFD T MEYERS ATTDRNLY Feb. 18, 1947. `w, F, MEYERS 2,416,193 I SCAVENGE PUHP DRIVE i Filed Feb; 2s, 1945 s sneetssneet s IN VEN TOR l"""ZL .5 y 'Bygg ATTORNEY WILLARD F'. MEYERS,

Patented Feb. 18, 1947 SCAVENGE PUMP DRIVE Willard F. Meyers, Demarest, N; IJ., assignor to Wright Aeronautical Corporation, a corporation of New York Application February 26, 1945, Serial No. 579,844 (c1. 10s- 5) `13 claims. 1

This invention relates to engine lubrication systems and is particularly directed to means for returning oil from an engine oil sump'to a supv yply reservoir therefor.

The lubrication systems of modern aircraft engines generally comprise a so-called dry-sump system in which an engine-driven oil pmp draws lubricating oil from a supply reservoir and pumps it under pressure to thc engine parts to be lubricated and from which parts the oil drains into a sump. In addition, a scavenge pump operates to return the oill from the sump through an oil cooler back into the supplyv reservoir. In order to insure removal of substantially all the oil from the sump to the reservoir under all engine-operating' conditions, the scavenge pump is provided with a capacity more than sufiicient for returning all the oil from the sump to the reservoir under the most adverse pump-Operating conditions. Thus,l the efciency of the conventional gear-type scavenge pump provided on aircraft engines decreases with decreasing pump inlet pressure and therefore the scavenge pump altitude operation, the scavenge lpump capacity is considerably in excess of the lubricating oil flow and therefore this pump returns a large quantity of air and other gases as well as oil back into the oil reservoir. The air and other gases thus returned .through the oil reservoir bythe scavenge pump become entrained within the oil and are only partially` separated therefrom within the oil reservoir. This entrainment of gases within the engine-lubricating oil considerably reduces the quantityof oil supplied by the enginedriven lubricating oil' pump. In addition, the presence of gases within the oil Ibeing pumped 'back through the oil cooler to the oil reservoir considerably reduces the eiilciency of the cooler.

It is an object of this invention to provide a when there is little or no oil in the engine sum-p,

the coupling runs empty thereby uncoupling the scavenge pump from the engine and when there is onlya small quantityl of oil in the sump, the

4ghydraulic coupling runs with a high degree ofl slip thereby providing only a low speed drive for the scavenge pump. It is a further object of this invention to use the coupling as a centrifugal pump for boosting the inlet oil pressure to the scavengel pump. .f

During engine operation,a large quantity of oil is thrown about the interior oi.' the engine crankcase by the moving parts of the engine and therefore considerable air and .other gases become entrained within the oil as it settles into the sump. It is a further object of this invention for using the hydraulic coupling as a centrifuge for separating at least some of the air and other gases thus entrained within the oil.

Other objects of this invention will become apparent upon reading the annexed detailed description in connection with the drawings in which:

Figure 1 is a schematic view of a conventional radial cylinder aircraft engine and the lubricationy system therefore embodying the invention;

Figure 2 is a sectional view along line 2-2 of Figure 4 illustrating one form of hydraulic coupling drive for the scavenge pump;

Figures 3 and 4 are sectional views taken along lines 3 3 and 4--4 respectively of Figure 2;

Figure 5 is a view similar to Figure 2 of a modiiled form of the invention; and

Figure 6 is a sectional view taken along lines 6-6 of Figure 5.

Referring first to Figure l, a conventional radial cylinder internal combustion engine illustrated at i0 is provided with a bank of radially- Vdisposed cylinders i2 mounted about the engine 20 and thence to the individual engine cylinders posed within the sump. The scavenge pump 30 is arranged to return oil from the engine sump lthrough conduit 3l, oil cooler 32, and conduit 34 Y under pressure to the various bearing surfaces of the engine. through passages such as 38.

In order to insurey substantially-complete re- 1 moval of all the oil from the engine sump under all operating conditions,l the scavenge pump 88 is provided with a capacity sufllcient to handle all the oil flow under the most adverse engineoperating conditions-for example, at high a1- 1 titudes since the efilciency of a gear-type Dump decreases with decreasing pump inlet pressure.`

Accordingly, at lower altitudes and, if' thescav'- 1 enge pump were geared directly to the engine as is the conventional practice, only a -portion of 3 the capacity of the pump would be used to rel turn oil back into the oil reservoir.

With the present invention the oil scavenge pump is driven from the engine through a hydraulic coupling 48. As illustrated in Figures 2 to 4, the scavenge pump 88 is disposed in the bottom of the sump 28 and is drivably splined to j a shaft 42 which, in turn. is drivably connected to the driven element 4 4 of the hydraulic coupling. The driving element. 48 of the hydraulic 1 coupling is driven from the shaft 48 through the splines 58 and the shaft 48 is drivably connected to an engine-driven shaft 52 through gears 5d and 58. Shaft d8 is hollow and extends into and above the bottom of the sump chamber 58. The

` driving coupling element 48 is provided with 1 one or l*more substantially radial openings 88 and with a conical hub 82 having an upwardly-extending apex on the axis of the hollow shaft d8.

The coupling' elements d5 and 48 have a mf tity of oil is thrown around inside the engineripheral clearance'as indicated at 'i545l through which the coupling oil is thrown outwardly into 1 the annular space S8 by the centrifugal force acting on the oil within the hydraulic coupling.

1 From the annular spacej88. the oil descends l through opening 88 to the scavenge pump inlet chamber 'I8 from which it is picked upby the j scavenge pump 38 which discharges the oil into the pump outlet. chamber 'I2 and the oil return line 8| back into the oil reservoir 24. If desired,

an oil strainer '|4jmay be disposed across the 1 i supply end of the hollow shaft 48 and a cylindrical oil strainer 18 may be disposed within the 1 pump inlet chamber 18 in alinement with the l opening 68. .For assembly purposes, the sump housing for the hydrauliccoupling and scavenge pump is built up from sections 18, 88, 82, 84, 88

and 88 secured' together and to the engine crankcase'by bolts' 88.

In ordertohelp'turn the oil, flowing downwardly through the -shaft 48, radially outwardly l48 to rotate therewith whereby the centrifugal force acting on the oil throws the oil radially outwardly j throughthe opening 88 -into the hydraulic coupling. helical twist to help yforce or pump the oil down 'Ihe vanes 92 are also provided with a.4

` the shaft 48.

With this construction, the engine-driven shaft 82 drives the scavenge pump 88 through the hywdraulic. coupling 48. l'When the coupling 48 is full of oil, it operates with very little slip to prothe output capacity of pump 38, the coupling will `ses begin to empty and its slip will increase thereby decreasing 'the speed and output of thescavenge pump. If there is no oil in the sump, the coupling will empty and there will be no engine drive to the scavenge pump. In this way lthe scavenge pump is only driven at a speed suillcient to remove the oil entering the coupling. Therefore,'the scavenge pump, when operating, will remain submerged in oil and will not add air or other gases to the oil it pumps back into the oil reservoir.

. yWith the aforedescribed construction, the'oil vwithin the hydraulic coupling is thrown out through the clearance 84 by the centrifugal force acting on the oil. Accordingly, the hydraulic pump not only provides a drive for the scavenge pumplbut it also acts as a centrifugal pump boosting the oil inlet pressure to the scavenge pump. This feature is quite desirable since, as

previouslynoted, the capacity of a conventional gear pump decreases with decreasing pump inlet pressure. Accordingly,y by thus substantially boosting the scavenge pump inlet pressure, the limiting 'altitude at which the pump stili has suf-` ficient capacity is substantially raised. Obviously this feature is quite important for aircraft engines designed for high altitude operation.,

During engine operation, a considerable'quanbefore it reaches the scavenge pump. Thus, as

oil and entrained air descend down the shaft t8, the vanes 92 cause lthis mixture to rotate with the shaft 48 and therefore the oil is thrown radially outwardly against the walls of the shaftl 88 by the centrifugal force acting thereon, thereby separating at least some of the air from the oil and leaving the air free to escape kup through the center of theshaft 48 back into the crankcase. In addition,vthe hydraulic coupling 48 also acts as a centrifuge such that the air accumulates .about the hub of the coupling from which it can escape up through the center of the shaft 48 since, as'descri-bed, the oil descends down the hol- 1 driven shaft |84 through gears |86 and |88 and a hollow shaft H8. However, in this embodiment ofthe invention, separate passages ||2'are pro- [vided through which the oil drains from the 'sump chamber I4 down into the hydraulic coupling |82. In addition, a passage I6, annular groove |I8 and a radial passage |28 in the hollow' shaft H8 connect the interior hub portion of the 'hydraulic coupling |82 with the interior of the hollow shaft H8. With this construction and as a result of the centrifuge action of the hydraulic coupling, the air separated from the oil within the coupling is free to escape back into the engine l crankcase through the hollow shaft H8.. The upper end yof shaft ||8 extends up into thesump o chamber ||4 above the normal level of'foii therein.

" vide a substantially-direct drive from the shaft 48 to the scavenge pump 88. If the quantity of l l' 1 oil entering the coupling 48 should drop below ,Thedrivenjcoupling element |22, of the hydraulic coupling |82 is drivably connected by a |24 is provided between the coupling elements I 00 and |22 and the centrifugal force, acting on the oil within the coupling, forces he oil out from the coupling into anannular space |30) and down through an opening |32 to an inlet chamber |34 of the invention the hydraulic coupling` provides a variable speed drive for the scavenge pump such that the speed of operation of the scavenge pump depends on the amount of oil available in the engine sump whereby the pump gears remain submerged in oil during pump operation. In addition, the hydraulic coupling serves to boost the inlet pressure to the scavenge pump and the hydraulic coupling acts as a centrifuge separating the air or other gases entrained or mixed with the oil in the sump. However, in Figures 2 to 4, the oil enters the coupling from the sump through the hollow coupling drive shaft 48 and the gases separated from the oilescape through the center of this shaft whereas in Figures 5 and 6 the sumpv oil enters the coupling through separate passages l2 and the separated gases escape through the hollow coupling drive shaft H0.

While I have described my invention in detail in its present preferred embodiment, it will be obvious to those skilled in the art, after understanding my invention, that various changes and modifications may be made therein without .departing from the spirit or scope thereof. I aim in the appended claims to cover all such modifications.

I claim as my invention:

1. In an engine, an oil sump, a scavenge pump for removing oil from said sump, and a hydraulic slip coupling having a chamber adapted to be loaded with oil from said sump to provide \a drive from said engine to said pump, said coupling chamber being serially disposed in the oil flow path between said sump and pump, the arrangement being such that substantially all the oil reaching the inlet side of said pump passes through said coupling chamber.

2. In an`engine, an oil sump, a scavenge pump for removing oil from said sump, and a rotatable hydraulic slip coupling loadable by oil fromsaid sump to provide a drive from said engine to said pump and to boost the inlet pressure to said air or other gases from the oil flowing from said sump to said pump. V

5. In an engine, an oil sump, a scavenge* pump for removing oil from said sump, and a hydraulic slip, coupling comprising first and second coupling elements drivably connected to said engine and pump respectively, said coupling elements denning a coupling chamber therebetween, the drive connection-'between said ilrst coupling element and engine including a hollow shaft having' any openend extending up into said sump, the interior of said hollow shaft being in communication with said annularj chamber adjacent the inner .diameter of said chamber.

6. In an engine, an oil sump, a scavenge pump for removing cil from said sump, and a hydraulic slip coupling comprising first and second coupling elements drivably connected to said engine and pump respectively, said coupling elements' defining therebetween a coupling chamber serially disposed in the oil flow path between vsaid sump and pump, the drive connection between said first coupling element and engine including a hollow shaft having an open end extending up intosaid sump, the interior of said hollow shaft being in communication with said annular chamber adjacent the inner diameter of said chamber. '1. In an engine', an oil sump, a scavenge pump for removing oil from said sump, a hydraulic slip coupling comprising first and second coupling elements drivably connected `to said engine and pump respectively, said coupling .elements del ilning a coupling chamber therebetween, the drive connection between said first coupling element and engine including a hollow shaft having an open end extending into said sump above the normal level of oil therein, the interior of said hollow shaft being in communication with said annular chamber adjacent the inner diameter of said chamber, and passage means independent of said hollow shaft providing for the flow of oil from said sump into said chamber, said passage means and chamber being serially disposed in the oil flow path between said sump and pump.

8. In an engine, an oil sump, a scavenge pump for removing oil from said sump, and a hydraulic slip coupling comprising first and second coupling elements drivably connected to said engine v and pump respectively, said coupling elements deflning a coupling chamber therebetween, the drive connection between said iirst coupling `element and engine including a hollow shaft providing an oil flow path between said sump and chamber. d

9. In an engine, an oil sump, a scavenge pump for removing oil from said sump, and a hydraulic slip coupling comprising iirst and second ,cou

pling elements drivably connected to said engine and pump respectively, said coupling elements to be loaded with oil from said sump to provide a drive from said engine to said pump, said coupling having an opening adjacent its outer periphery through which oil is forced from said chamber to the inlet of said pump by the centrifugal force acting on the oil within said cham- .l

defining a coupling chamber therebetween, the drive connection between s aid first coupling element and engine including a hollow shaft providing an oil ow path between said sump and chamber. said oil flow path and chamber ybeing serially disposed in the oil ow path between said sump and pump.

10. In an engine, an oil sump, a scavenge pump for removing oil from said sump, a hydraulic slip coupling comprising ilrst and second coupling elements drivably connected to said engine and pump, respectively, said coupling elements de-- ning a coupling chamber therebetween, the drive connection between said rst coupling element and engine including a hollow shaft providing an oil flow path between said sump and chamber,

g 7 l l and a plurality of vanes withinsaid'hoilow shaft for causing rotation of the oil therein-with said shaft. l

; 11. In an engine.' an oil sump, a scavengepump for lremoving oil from said sump,l and a hydraulic ,-ber,'power means, and a rotatable hydraulic slip slip coupling comprising iirst and second coupling elements drivably connected to said engine and pump respectively, vsaid coupling lelements dening a coupling chamber therebetween, the y v drive connection .between said first coupling element and engine including a hollow shaft providing an oil flow path between said sump and chamber, and a plurality of vanes within said hollow shaft for causing rotation of all therein with said shaft, said vanes having a substantiallyhelical twist about the axis of said shaft.

l12. In combination, a chamber for a liquid, a pump for removing said liquid from4 said chamber, power means, and a hydraulic slip coupling having a space adapted to be loaded with liquid from said chamber to provide .a drive from said power means to said Pump, 'said coupling space y being serially disposed in the liquid ow path between said chamber and pump, the arrangement being such thatsubstantially all the oil reaching the inlet side of said pump passes through said coupling chamber.

313. In combination, a chamber for a liquid, a' pump forremoving said liquid from said chamcoupling having an annular space adapted to be i loaded with liquid from said Tchamber to provide a drivefrom said power means to said pump, said coupling annular space being serially disposed in the liquid iiow path between said chamber .and pump and having an opening vadjacent its outer periphery through which liquid is forced from said chamber to the inlet vof said pump by. thel centrifugal force acting on the liquid in said chamber, the arrangement being such that. substantially all the oil reachingthe inletsideI of said pump passes through said coupling chamber.

WIILARD F. MEYERS. i REFERENCES crrm,

The following references are of record in' the file of this patent:

UNITED STATES PATENTS British, i926 

